Are levaling kits installed by the manufacturer proir to delivery to dealer?

I've noticed other chevy's with a straight stance, direct from the dealer! (not the snail truck effect.) My front air dam likes to bottom out sometimes. Just need about 2 more inches of clearance. Don't want a suspensin lift, I like my MPG, with stock rims and tire diameter. I want a smooth ride. Maybe Chevy uses a kit during original assembly of the truck?